SOLUTION: The elevator in the Washington Monument takes 75 seconds to travel 500 feet to the top floor. What is the speed of the elevator in miles per hour? Give your answer to two signifi

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Question 153600: The elevator in the Washington Monument takes 75 seconds to travel 500 feet to the top floor. What is the speed of the elevator in miles per hour? Give your answer to two significant digits.
Found 2 solutions by Earlsdon, Edwin McCravy:
Answer by Earlsdon(6294)   (Show Source): You can put this solution on YOUR website!
You need to convert: 500ft per 75 secs into miles per hour.
To convert ft/sec into mph, you would divide the number of feet by 5,280 feet/mile, and to convert seconds to hours, you would divide the number of seconds by 3,600 secs/hour.
Let's see how this works:
(500 ft)/(75 secs) = (500 ft/5280 ft per mile)over(75 secs/3600 secs per hour)= 4.54 miles per hour.
Answer by Edwin McCravy(20056)   (Show Source): You can put this solution on YOUR website!
Edwin's solution:
The elevator in the Washington Monument takes 75 seconds to travel 500 feet to the top floor. What is the speed of the elevator in miles per hour? Give your answer to two significant digits.




Now use the fact that  to create
a unit fraction to cancel away the 's.  Since
 is in the top, we want to create a unit 
fraction with  on the bottom, so we create
the unit fraction . So we multiply
by that fraction:

x.

and then cancel away the 's.

x

Now use the fact that  to create
a unit fraction to cancel away the 's.  Since
 is in the bottom, we want to create a unit 
fraction with  on the top, so we create
the unit fraction . So we multiply
by that fraction:

xx.

and then cancel away the 's.

xx. 

Now use the fact that  to create
a unit fraction to cancel away the 's.  Since
 is in the bottom, we want to create a unit 
fraction with  on the top, so we create
the unit fraction . So we multiply
by that fraction:

xxx.  

and then cancel away the 's.

xxx. 

Now the only units that are not canceled away are  
on the top and the  on the bottom.







Rounding to two significant digits:



Edwin
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